This invention relates generally to an improved method of helically winding wire on an endless ring-shaped core and an apparatus for practicing such method, and more particularly to a method of and an apparatus for fixing the wire end to the core before winding the wire on the core.
The use of a machine for helically winding wire on a ring-shaped core has been proposed heretofore, for example, in U.S. Pat. No. 1,570,821. This patent discloses means for accomplishing helical winding of wire on a ring-shaped core by revolving the ring-shaped core in its peripheral direction while simultaneously rotating the wire drum relatively to the core so that the drum will turn around a part of the core and will also pass through the ring of the core. However, the patent makes little explanation of the manner in which the leading end of the wire is or may be fixed to the core before commencing the winding of the wire thereon.
Generally, fixing of the leading end of the wire to the core is practiced in one of the following ways:
I. The worker holds with his hand the leading end of the wire on the core until the wire is sufficiently wound on the core to secure the leading end of the wire against becoming loose thereon; and
II. The leading end of the wire is temporarily joined to the core by soldering or other similar means.
However, these methods also involve many defects and difficulties which hamper productivity of the ring-shaped core having a helical winding thereon. That is, in the case of manual fixing as mentioned in (i) above, since the core must be revolved in its peripheral direction, the worker himself must go round the core while grasping the foremost end of the wire and a part of the core. This is extremely troublesome and also makes it impossible to attain the best winding effect of the machine. On the other hand, in the case of the soldering method mentioned in (ii), such problems arise as the soldering work itself requiring much time, the work being difficult and requiring skill and experience, and finally solder must be removed following completion of the winding. Thus, either of these methods is bad from the view of workability and also from the view of being low in reliability. Further, in view of the fact that formation of the winding layers is governed by the delicate positional relation between the wound wire and its foremost end, it must be said that it is practically impossible to perform such winding, that is, to produce the ring-shaped helical beads, on a mass production scale with a machine by using such conventional techniques having such poor reliability.